Of all the viral stories that come and go online, few seem as long-lived as the dress that was either blue+black or gold+white, depending on who was looking. That story broke initially in 2015 - and yet I mentioned it in class yesterday and every student there knew what I was talking about - and had strong feelings as to what colour the dress actually was.
And then co-incidentally, I can across this image online over the weekend, which brings me as close as I think I will ever be to understanding what is going on.
The image build on the best explanation I found for the phenomenon back in 2015, from Wired magazine.
In summary, what I learned there was this. First of all, the dress really was black and blue. People who saw it in reality all agreed on that. The effect that caused such confusion only arose from a photograph (taken at a wedding) that was taken in quite dim light.
And why do we see it differently? Because.....'Without you having to worry about it, your brain figures out what colour light is bouncing off the thing your eyes are looking at, and essentially subtracts that colour from the "real" colour of the object. "Our visual system is supposed to throw away information about the illuminant and extract information about the actual reflectance," says Jay Neitz, a neuroscientist at the University of Washington.
The cartoon above is an attempt to visualise that, and if I understand it correctly, its like this: in ordinary bright lighting we would all see the strong blue and black colours, but the lighting in the photo was more like that in the shaded area. And the parallel bars show how our varying interpretations aren't as far apart as they seem at first.
So those of us who are more inclined to see blue see those areas as a shade of blue, whereas those who are less inclined to see blue, see it as something closer to the yellow and white shades to the right. But what is particularly interesting about this to me is that, unlike optical illusions, this isn't a case of learning how to look at something differently. In the famous wineglass-or-face illusion, we can all (eventually) see either the wine glass or the people's faces.
Whereas with the dress, those of us who see blue/black will always see blue/black - and those who see gold and white will always see gold and white. Because its not just a case of how we look at it, its down to our ability to see colour (particularly blue) - and that is hardwired in our brains and varies from person to person. What the illustration above shows us is that there really is no 'right' way of seeing this.
It's not that some of can see blue easily and others lack that ability. You could just as precisely say that some of us are capable of not seeing blue - which might have advantages seeing things in the open when the sky tends to be blue - and that the rest of us lack the ability to filter blue out.
The truth is we're just (very slightly) different, and that that's fine!
I found the cartoon image here: Tom Chivers (@TomChivers) / Twitter
And the image apparently comes from here: Tom Chivers on Twitter: "image credit: Figure design by Kasuga~jawiki; vectorization by Editor at Large; "The dress" modification by Jahobr. Creative Commons license https://t.co/TzGzlVoAa9" / Twitter